Nick Clegg has said that the government should be looking at treating drug addiction as much as a health issue as a criminal one. Photograph: Peter Macdiarmid/Getty

Nick Clegg has accused the Conservatives of refusing to look "imaginatively" at drug laws after senior police officers said current policies are not working.

The deputy prime minister said his coalition partners are blocking Lib Dem efforts at reform and suggested that drug addiction should be treated more as a health problem.

Speaking on BBC Three's Free Speech, he said legalising all drugs was not "necessarily the right option", but the UK is not winning the drugs war with its current approach.

"I think we keep banging our head against the wall and in fact I find it very frustrating that my Conservative coalition partners are not prepared to look more openly, imaginatively," he said.

"You've got very senior police officers now coming out saying that the war on drugs is failing, that we should treat drug addiction as much as a health issue as a criminal justice one. All these kinds of things we need to look at."

The interview was broadcast after Clegg appointed Norman Baker as the new Lib Dem drugs minister, who will take on a review of how 10 other countries deal with drugs.

Baker previously said cannabis is "no more harmful than alcohol or tobacco" when Tony Blair announced he would downgrade cannabis to class C in 2001.

This week, Baker said he hoped to bring more "liberal input" to the home office.

Asked about his views on drugs on the BBC's World at One programme, Baker was keen to stress that he does not encourage any use of drugs.

"I think it's important we're evidence-based in what we do," he said.

"I know that drug use at lowest level since records began and more people are going into treatment.

"The key thing is I don't encourage any use of drugs or any harmful substances. I hope people will drink less and smoke less as a matter of fact.

"Where we want to get to is making sure where people do use drugs they can be persuaded out of that habit and we don't end up with people committing crime in order to feed their habit."

Before he was fired in the reshuffle, Baker's predecessor, Jeremy Browne, was gathering evidence from other countries on their drug policy, including Portugal's efforts to reduce drug use by removing criminal penalties for personal possession without making drugs legal.

Browne had expressed doubts about relaxing laws on cannabis, claiming the drug is "getting much stronger and potentially more harmful", while Theresa May, the home secretary, has also said the government "does not believe there is a case for fundamentally re-thinking the UK's approach to drugs".

However, last month, one of England's most senior police officers called for class-A drugs to be decriminalised and for the policy of outright prohibition to be radically revised.

Mike Barton, Durham's chief constable, suggested the NHS could supply drugs to addicts, breaking the monopoly and income stream of criminal gangs.

On Wednesday evening, Ed Miliband, the Labour leader, told Free Speech he does not believe in decriminalisation but he is in favour of more education.

"We know the effect of drugs can be harmful and I don't want us to be saying to young people 'we should legalise drugs, or decriminalise drugs'," he said.

"What I do want to say to young people is let's have proper education about drugs in schools so that people understand the dangers of drugs. Let's have early intervention where people are going off the rails through drug use and let's have proper drug treatment.

"I don't think the answer is decriminalisation or legalisation, I think the answer lies in better education, better prevention and better treatment."